Immediate Effect of Lumbar Mobilization on Paraspinal Muscle Stiffness

This randomized controlled crossover study will investigate the immediate effect of central posteroanterior lumbar mobilization on the intrinsic stiffness of the erector spinae and multifidus muscles in healthy adults without low back pain. Twenty-four participants will complete two experimental visits in randomized order. During one visit, participants will receive Maitland Grade III++ central posteroanterior mobilization at the L4 vertebral level, while during the other visit they will receive a sham mobilization condition involving gentle rhythmic pressure. Muscle stiffness will be assessed using shear wave elastography immediately before and after each intervention.